Molded product and manufacturing method thereof

ABSTRACT

A molded product and a method of manufacturing the same are disclosed, in which the insulating layer of uniform thickness is formed in a narrow clearance between plural metal bodies. Surroundings of metal plates spaced at specified intervals are covered with insulating polymer to insulate them electrically. A spacer polymer which consists of insulating polymer whose melting point is T 1  is arranged between the metal plates, and a molded part which consists of insulating polymer whose melting point is T 2 (&lt;T 1 ) covers surroundings of the metal plates and the spacer polymer.

BACKGROUND OF THE INVENTION

The present invention relates to a molded product and a method ofmanufacturing the same, in which surroundings of each of metal bodiesspaced at a constant interval is covered with insulating polymer toinsulate plural metal plates electrically.

The technique by which metal bodies are covered with a molded partcomprised of insulating polymer is generally used to secure thereliability over the long term when insulating between metal bodies ofrelatively high average electric field strength of hundreds of V/mm ormore with insulating polymer. As a technique by which the moldingcoating is done, the technique by which insulating polymer isinjection-molded or extrusion-molded to obtain a target shape with thepart to be exposed of metal bodies held is most frequently used.

As shown in FIG. 10A, two metal plates 101,102 which have pluralterminal parts 101 a, 102 a are coated with molded part 103 in usualmolded product 100. Terminal parts 101 a and 102 a of metal bodies101,102 can be exposed from molded part 103. As shown in FIG. 10B andFIG. 10C, metal bodies 101, 102 are spaced at specified intervals andinsulated to each other.

Metal bodies 101, 102 are set in cavity 113 of injection molding die 110as shown in FIG. 11, and fixed in cavity 113 with terminal part 101 a,102 a placed between upper dies 111 and lower dies 112. Afterwards,molten resin 116 is supplied to cavity 113 from at least one shootinghead 115 connected fluidly thereto. After the supply of molten resin 116is completed, molded part 103 is formed by cooling molten resin 116 tosolidify, and molded product 100 shown in FIG. 10 is obtained.

The prior art described above is disclosed, for example, in JapanesePatent Application Laid-Open No. 2003-143868.

SUMMARY OF THE INVENTION

There are three main problems when the insulative molded productdescribed above is molded by injection molding.

(a) When the resin with a high melt viscosity is used, or when the areasof metal plates 101, 102 are large, it is difficult to decrease theclearance 105 (insulation thickness) between the metal bodies.

When clearance 105 between metal bodies 101, 102 becomes narrow to theareas of metal bodies 101, 102, the injection molding material (moltenresin 116) becomes hard to enter between metal bodies 101,102.Therefore, it is difficult to form an insulating layer not defectivebetween metal bodies 101,102. Although nylon which has small viscosityat melting is used to perform the injection molding with a high degreeof accuracy, the clearance 105 where desirable injection molding can beperformed to metal bodies 101, 102, one side length of which is about200 mm is about 0.5 mm. Molten resin 116 does not spread to the edge ofcavity 113 (every corner) when clearance 105 is smaller than the value.Therefore, problem may occur in such a case. Inflow shortage of such amaterial causes the decrease in the insulating property between metalbodies 101,102.

(b) It is difficult to maintain clearance 105 between metal plates101,102 uniformly.

It is difficult to hold metal bodies 101, 102 when tried to insulaterelatively thin metal plates 101, 102 spaced at specified intervals, andcover the outside of metal bodies 101, 102 with molded part 103. As aresult, metal bodies 101, 102 are transformed by the pressure ofinjected molten resin 116, and the homogeneity of clearance 105 is lost.When the homogeneity of clearance 105 is lost, the electric fieldconcentrates on the part with a narrow interval, the defect part of theinsulation structure when the voltage is applied to metal bodies 101,102. As a result, long-term reliability of the article is spoiled

(c) It is difficult to make insulating material (insulating polymer) andmetal bodies 101, 102 stick.

Although surroundings of metal plates 101, 102 or clearance 105 betweenthem becomes a part on which the electric field concentrates when thevoltage is applied to metal bodies 101, 102, the insulation performancedecreases when flaking off is caused on the interfaces of metal bodies101, 102 and the insulating material by the heating and cooling repeatedby the change of the turn-on environment (or, system requirements) or by“shrinkage” when the insulating material is molded, and the possibilitythat the dielectric breakdown is caused rises. A partial electricdischarge may occur on the interface of metal bodies 101, 102 and theinsulating material, and lifetime may be remarkably decreased.Therefore, it is necessary to bond insulating material and metal bodies101, 102 strongly, and mold release characteristics deteriorate when theinsulating material contains the adhesive. In addition, the viscosity ofmolten resin 116 rises, and the formability deteriorates. Further, thereis a possibility that the adhesive flows by the injection pressure ofthe insulating material when the adhesive is spread on metal bodies 101,102 beforehand, and the bonding power varies.

In consideration of the above-mentioned circumstances, an object of thepresent invention is to provide a molded product and a method ofmanufacturing the same, in which the insulating layer of uniformthickness is formed in a narrow clearance between plural metal bodies.

To achieve the above-mentioned object, the present invention in oneaspect resides in a molded product, in which surroundings of metalplates spaced at specified intervals are covered with insulating polymerto insulate them electrically comprises a spacer polymer arrangedbetween said metal plates, which consists of insulating polymer whosemelting point is T1, and a molded part, which covers surroundings ofsaid metal plates and said spacer polymer, and consists of insulatingpolymer whose melting point is T2 (<T1).

Preferably, the principal ingredient of said insulating polymer ofmelting point T1 is aromatic polymer, and the principal ingredient ofsaid insulating polymer of melting point T2 is polyolefine.

Optionally, the bonding layer composed of the adhesive that meltingpoint T3 is in the relation of T3<T1 is provided between said metalplates and said spacer polymer, and between said metal plates and saidmolded part. Preferably, the first and second bonding layers composed ofthe adhesive that melting point T3 is in the relation of T3<T1 areprovided between said metal plates and said spacer polymer, and betweensaid metal plates and said molded part, respectively, and each adhesivewhich composes said first and second bonding layers has highcompatibility.

In another aspect, the present invention resides in a method ofmanufacturing a molded product, in which surroundings of metal platesspaced at specified intervals are covered with insulating polymer toinsulate them electrically, comprises the steps of arranging a firstsheet material composed of insulating polymer whose melting point is T1between said metal plates spaced at specified intervals, arranging asecond sheet material composed of insulating polymer whose melting pointis T2 (<T1) outside of the outermost metal plates, hot-pressing moldinga laminate of the metal plates, the first sheet material, and the secondsheet material at a temperature higher than T2 but lower than T1,melting the second sheet material while securing the interval betweenthe metal plates by the first sheet material, and covering thesurroundings of the metal plates and the first sheet material with themolded part composed of insulating polymer whose melting point is T2.

In a further aspect, the present invention resides in a method ofmanufacturing a molded product, in which surroundings of metal platesspaced at specified intervals are covered with insulating polymer toinsulate them electrically, comprises the steps of arranging a firstsheet material composed of insulating polymer whose melting point is T1between said metal plates spaced at specified intervals, arranging alaminate of the metal plates and the first sheet material in the cavityof the injection mold, injecting insulating polymer whose melting pointis T2 (<T1) heated and melted at a temperature higher than T2 but lowerthan T1 into the cavity, and covering the surroundings of the metalplates and the first sheet material with the molded part composed ofinsulating polymer whose melting point is T2 while securing the intervalbetween the metal plates by the first sheet material.

Optionally, a plurality of said first sheet materials are arrangedbetween the metal plates.

Optionally, the method of manufacturing a molded product furthercomprises the steps of providing as one first bonding layers and secondbonding layers which consist of adhesive whose melting point T3 is inthe relation of T3<T1 on surfaces of the first sheet material andsurfaces on the metal body sides of the second sheet materials,respectively, and after hot-pressing molding, bonding the first sheetmaterial to said metal plates by the first bonding layers, and saidmolded part to said metal plates by the second bonding layers.Preferably, in the method of manufacturing a molded product, eachadhesive which composes the first bonding layer and the second bondinglayer has compatibility, and the first bonding layer are bonded to thesecond bonding layer.

Optionally, the method of manufacturing a molded product furthercomprises the steps of providing as one first bonding layers whichconsist of adhesive whose melting point T3 is in the relation of T3<T1on surfaces of the first sheet material, and after hot-pressing molding,bonding the first sheet material to said metal plates by the firstbonding layers.

Plural metal plates can be coated with insulating polymer according tothe present invention. Moreover, it is possible to insulate betweenplural metal plates by a thin and uniform insulating layer.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a sectional view of the spacer polymer sheet used for amanufacturing method of the molded product according to a preferredembodiment of the present invention.

FIG. 2 is a sectional view of mold polymer sheet used for amanufacturing method of the molded product according to a preferredembodiment of the present invention.

FIG. 3A and FIG. 3B are structural drawings of the molded productaccording to a preferred embodiment of the present invention. FIG. 3A isa plan view, and FIG. 3B is a sectional view taken along the line 3B-3Bof FIG. 3A.

FIG. 4 is a view showing the lamination state of a laminate used tomanufacture the molded product according to a preferred embodiment ofthe present invention.

FIG. 5 is a view showing the state where the laminate of FIG. 4 isarranged between hot pressing plates of a hot pressing machine.

FIG. 6 is a view showing the state where the hot pressing mold wasperformed to the laminate of FIG. 5.

FIG. 7 is a sectional view of a first modification of FIG. 6.

FIG. 8A and FIG. 8B are views showing the modification of the frame bodyused for a manufacturing method of the molded product according to apreferred embodiment of the present invention. FIG. 8A is a plan view,and FIG. 8B is a view seen from a direction of arrow 8B of FIG. 8A.

FIG. 9 is an explanatory drawing of a manufacturing method of the moldedproduct according to another preferred embodiment of the presentinvention.

FIG. 10A, FIG. 10B and FIG. 10C are structural drawings of a general busbar. FIG. 10A is a plan view, FIG. 10B is a view seen from a directionof arrow 10B of FIG. 10A and FIG. 10C are a sectional view taken alongthe line 10C-10C of FIG. 10A.

FIG. 11 is an explanatory drawing of the conventional manufacturingmethod of a molded product.

DETAILED DESCRIPTION OF THE INVENTION

Hereafter, a preferred embodiment of the present invention will beexplained based on attached drawings.

FIG. 3 is structural drawing of the molded product according to apreferred embodiment of the present invention. FIG. 3A is a plan view,and FIG. 3B is a sectional view taken along the line 3B-3B of FIG. 3A.

Surroundings of plural metal plates 31 and 32 (two metal plates in FIG.3B) are covered with molded part 33 in a mold article according to thisembodiment as shown in FIG. 3A and FIG. 3B.

Spacer polymer part 34 composed of insulating polymer of melting pointT1 and adhesive of melting point T3 (T3<T1) is provided between metalplates 31 and 32. Surroundings of spacer polymer part 34 and metalplates 31 and 32 are covered with molded part 33 composed of insulatingpolymer of melting point (or softening point) T2 (<T1). Projection parts(terminal part) 31 a and 32 a projects from molded part 33.

A method of manufacturing a molded product according to this embodimentwill be explained based on attached drawings.

First of all, as shown in FIG. 1, first bonding layers 12 a, 12 bcomposed of the adhesive whose melting point T3 is in the relation ofT3<T1 are provided as one on the surface (upper and lower sides inFIG. 1) of first sheet material 11 composed of insulating polymer whosemelting point is T1 to make spacer polymer sheet 10. Optionally, firstbonding layer can be provided only on one side of first sheet material11. Further, first bonding layer need not necessarily provide.

On the other hand, as shown in FIG. 2, second bonding layer 22 composedof the adhesive whose melting point T3 is in the relation of T3<T1 isprovided as one on the surface on metal body side (under face in FIG. 2)of second sheet material 21 composed of insulating polymer whose meltingpoint is T2 (<T1) to make mold polymer sheet 20. Further, the secondbonding layer need not necessarily provide.

Next, as shown in FIG. 4, laminate 40 is formed by placing spacerpolymer sheet 10 between metal plates 31 and 32, and laminating moldpolymer sheet 20 on metal plates 31 and 32 so that the surface of theside of second bonding layer 22 may contact the metal sheet. At thistime, the lamination is performed so that a part of metal plates 31 and32 may protrude beyond laminate 40. The points of metal plates 31 and 32which protrude from laminate 40 become terminal parts 31 a and 32 a.Optionally, a plurality of spacer polymer sheets 10 can be placedbetween metal plates 31 and 32. The clearance between metal plates 31,32 of molded product 30 described later can be freely adjusted byadjusting the number of spacer polymer sheets 10. When the number ofmetal plates is three sheets or more, mold polymer sheets 20 arearranged only outside of two outermost metal plates.

Laminate 40 is arranged between hot pressing plates 41 and 42 of the hotpressing machine. Terminal part 31 a is supported by upper dies 43 andlower dies 44 as shown in the FIG. 5, and positioned on step part 44 aof lower dies 44. Moreover, terminal part 32 a is supported by upperdies 45 and lower dies 46, and positioned on step part 45 a of upperdies 45. At least one of hot pressing plates 41 and 42 is connected witha cylinder etc. (not shown) of an oil pressure piston, and can movefreely in directions of arrows A1 and A2, that is, in a direction wherelaminate 40 is compressed.

Next, the hot pressing mold is carried out to laminate 40 at atemperature higher than T2, but lower than T1. The pressure when the hotpressing mold is carried out is the pressure by which molten polymer 63(described later), second sheet material 21 melted, can be transformedand drifted sufficiently, and is not limited to the specified value.

As shown in the FIG. 6, first sheet material 11 of spacer polymer sheet10 is not melted when the hot pressing mold is carried out, and theshape is maintained. Therefore, the interval (clearance) correspondingto the thickness of first sheet material 11 can be almost securedbetween metal plates 31 and 32. Moreover, this clearance becomes uniformover the direction of the surface of metal plates 31 and 32. Further,second sheet material 21 of each mold polymer sheet 20 is melted by thehot pressing processing, and becomes molten polymer 63. This moltenpolymer 63 flows so as to bury space 61 formed by hot pressing plates41, 42, dies 43, 44, and dies 45, 46. Moreover, each adhesive whichcomposes first bonding layers 12 a, 12 b, and second bonding layers 22is melted partially by the hot pressing processing because melting pointT3 is less than T1 as well as T2, and flowed along with molten polymer63. Temperature T3 can be either one of T3≦T2 and T3≧T2.

Metal plate article 30 shown in FIG. 7 is obtained by molten polymer 63spread in space 61 being cooled, and being solidified. First sheetmaterial 11 and each of metal plates 31, 32 are bonded through remainingfirst bonding layers 12 a and 12 b. Moreover, the major part of moldingsides (under face in FIG. 7) of metal plate 31 and molded part 33, andthe major part of molding sides (top face in FIG. 7) of metal plate 32and molded part 33 are bonded through remaining second bonding layers22. Spacer polymer part 34 comprises first sheet material 11 andremaining first bonding layers 12 a and 12 b. When the first bondinglayer is not provided on first sheet material 11, the first sheetmaterial itself becomes spacer polymer part 34.

Here, the manufacturing of molded product 30 comes to be easy and tostabilize as the difference between the melting point of insulatingpolymer whose melting point is T2 which composes first bonding layers 12a, 12 b and that of insulating polymer whose melting point is T1 whichcomposes second bonding layers 22 becomes large.

Polymer material which contains aromatic polymer as a principalingredient is suitable for insulating polymer whose melting point is T1.Moreover, polymer material or various elastomers which containspolyolefine as a principal ingredient is suitable for insulating polymerwhose melting point is T2. In a word, it is desirable that the firstpolymer which has first adhesion mechanism by which strong bonding forthe aromatic polymer material is obtained is used for insulating polymerwhose melting point is T1. On the other hand, it is desirable that thesecond polymer which has second adhesion mechanism by which strongbonding for the metallic material is obtained is used for insulatingpolymer whose melting point is T2. It is more desirable that eachpolymer has high compatibility. When second bonding layers 22 areprovided on the sides of spacer polymer sheet 10 of metal plates 31, 32,first bonding layers 12 a, 12 b, and second bonding layers 22 areadjacent. At this time, first bonding layers 12 a, 12 b, and secondbonding layers 22 are strongly bonded when first polymer and secondpolymer have high compatibility, and metal plates 31, 32, and firstsheet material 11 can be bonded more strongly consequently.

In the first adhesion mechanism, styrenic elastomer (polymer) which hasstyren block with high compatibility with aromatic polymer is used as anadhesive. The styren block part and the aromatic polymer in the adhesiveare melted into each other when the adhesive and the aromatic polymermaterial are heated and pressurized. As a result, the adhesive and thearomatic polymer material are bonded strongly. Here, the aromaticpolymer means polymer which has an aromatic ring in the principal chain.For instance, polyphenylene ether (PPE), polyetherimide (PEI),polycarbonate (PC), polyether sulphone, polyimide, polyphenylenesulfide, polysulfone, polyether ether ketone, etc. can be used, but itis not limited to the above substances. On the other hand, as styrenicelastomer which has the styren block, styrene ethylene butylene styrenecopolymer (SEBS), styrene ethylene propylene styrene copolymer (SEPS),diblock copolymer such as styrene butylene styrene copolymer (SBS),diblock copolymer such as styrene butadiene rubber hydrogenised can beused.

Moreover, in the second adhesion mechanism, the epoxy radical part orthe acid radical part of polymer produces hydrogen bond with the watermolecule or the oxide of the metal surface by using the acid-modified orepoxy-modified polymer as an adhesive. As a result, the adhesive and themetal are bonded strongly. Maleic acid modification in the acidmodification of polymer is typical acid -modification. There are, forinstance, elastomer polyethylene (PE) such as SBS, SEBS, polyisobutylene(PIB), etc. and polymer of olefinic system such as polypropylene asacid-denaturated polymer. On the other hand, there are substanceobtained by changing the copolymer of polyethylene and polystyrene toglycidyl, and substance obtained by changing the copolymer of ethyleneglycidyl methacrylate copolymer (EGMA) and polystyrene (PS) as polymerwhich has the epoxy radical.

Spacer polymer part 34 (see FIG. 3B) which is a thin insulating layercan be uniformly formed by coating molded part 33 with spacer polymersheet 10 arranged between metal plates 31 and 32 according to amanufactu ring method of a molded product according to this embodiment.In a word, it is possible to coat metal plates 31, 32 with molded part33. Moreover, it is possible to insulate metal plates 31 and 32 througha thin, uniform insulating layer. The formation of this spacer polymer34 is influenced by neither the size of the areas of metal plates 31 and32 nor the size of the clearance between metal plates 31 and 32.Further, the thickness of spacer polymer 34, that is, the clearancebetween metal plates 31 and 32 is uniform in a direction of the surfaceof the metal plates.

Moreover, molded part 33 and spacer polymer part 34 of the moldedproduct according to this embodiment are formed not by the injectionmolding like the conventional manufacturing method shown in the FIG. 11but by the hot pressing mold. In a word, molded part 33 and spacerpolymer part 34 can be manufactured by using simple frame body composedof dies 43, 44, dies 45, 46 and hot pressing plates 41, 42 shown in FIG.6. Namely, an expensive dies for an injection molding need not be used.Therefore, molded product 30 can be manufactured cheaply.

The shape and the thickness of second sheet material 21 used tomanufacture molded product 30 according to this embodiment are adjustedfor the volume to increase more than at least necessary amounts of thevolume only by 10-40% in consideration of the volume of final moldedpart 33. In other words, the shape and the thickness of second sheetmaterial 21 are adjusted so that the amount of the overflow of moltenpolymer 63 may be 10% to 40% of the actual amount of volume of moldedpart 33. The shape reproducibility of molded part 33 can be improved bytaking the amount of the overflow of molten polymer 63 enough.

Moreover, when metal plates 31 and 32 are coated with molded part 33,the bond strength between metal plates 31, 32 and molded part 33, thatis, the magnitude of peel strength between metal plates 31, 32 andmolded part 33 becomes a main factor which determines the insulationperformance of molded product 30. Therefore, metal plates 31, 32 andmolded part 33 are bonded through the adhesive in molded product 30according to this embodiment. Concretely, the bonding layers are formedon the surfaces of first sheet material 11 and second sheet material 21,the surfaces of metal plates 31, 32 or the surfaces of first sheetmaterial 11, second sheet material 21, and metal plates 31, 32beforehand. As a result, metal plates 31, 32 and molded part 33 can bebonded uniformly and strongly. It is possible to maintain excellentlythe insulation performance of molded product 30 over a long period oftime.

The bond strength of adhesive of insulating polymer whose melting pointis T2 and metal plates 31, 32 can be freely adjusted by adjusting anamount of the acid modification (or, epoxy modification) of acidmodification (or, epoxy modification) polymer. Moreover, the bondstrength of adhesive of insulating polymer whose melting point is T1 andfirst sheet material 11 can be freely adjusted by adjusting an amount ofthe styrene in the styren block part of styrenic elastomer.

For instance, molded product 30 according to this embodiment is suitablefor a mold type power supply bus bar.

Further, although molded part 33 is formed by using frame body composedby hot pressing plates 41, 42, dies 43, 44, and dies 45, 46 in thisembodiment as shown in FIG. 6, the present invention is not limited tosuch structure. Optionally, it is possible to form molded part 33 byusing lower metal frame 81 and upper metal frame (not shown) shown inFIG. 8A and FIG. 8B as a frame body. Lower metal frame 81 corresponds tothe one that hot pressing plate 42, and lower dies 44, 46 areintegrated, and mold polymer sheet 20, metal plate 31, and spacerpolymer sheet 10 are accommodated in space part 82 of lower metal frame81. On the other hand, upper metal frame corresponds to the one that hotpressing plate 41 and upper dies 43, 45 are integrated, and metal plate32 and mold polymer sheet 20 are accommodated in the space part of theupper metal frame.

Next, another embodiment of the present invention will be explained withreference to attached drawings.

In the manufacturing method of a molded product according to theabove-mentioned embodiment, the molded part is formed by the hotpressing process. On the other hand, the molded part is formed by aninjection molding process in the manufacturing method of a moldedproduct according to this embodiment.

Concretely, spacer polymer sheet 10 is made by providing first bondinglayers 12 a, 12 b composed of the adhesive whose melting point T3 is inthe relation of T3<T1 on the surfaces (upper and lower surfaces inFIG. 1) of first sheet material 11 composed of insulating polymer whosemelting point is T1 first shown in FIG. 1.

Next, laminate 97 shown in FIG. 9 is formed by placing spacer polymersheet 10 between metal plated 31 and 32 and laminating them. At thistime, the lamination is performed so that a part of metal plates 31, 32may protrude beyond the laminate 97. Points of metal plates 31, 32 whichprotrude beyond laminate 97 forms terminal parts 31 a, 32 a. Further,optionally, it is possible to place a plurality of spacer polymer sheets10 between metal plates 31 and 32. The clearance between metal plates 31and 32 as described later can be freely adjusted by adjusting the numberof spacer polymer sheets 10 to be placed.

After laminate 97 is arranged between hot pressing plates of the hotpressing molding machine, the heating processing is carried out. As aresult, first bonding layers 12 a, 12 b is melted, and metal plates 31,32 and first sheet material 11 are bonded through first bonding layers12 a, 12 b. Then, bonded laminate 97 is set in cavity 93 of injectionmolding dies 90. Metal plates 31 and 32 are fixed in cavity 93 withterminal parts 31 a, 32 a placed between upper dies 92 and lower dies91. Then, molten polymer 96 is supplied to cavity 93 from at least oneinjection head 95 connected fluidly to cavity 93. Molten polymer 96 isthe polymer made by heating insulating polymer whose melting point is T2(<T1) at a temperature higher than T2 but lower than T1 and melting it.

First sheet material 11 of spacer polymer sheet 10 does not melt at thisinjection molding processing, and thus its shape is maintained.Therefore, the interval (clearance) for the thickness of first sheetmaterial 11 is almost secured between metal plates 31 and 32. Thisclearance becomes uniform over a direction of the surfaces of metalplates 31, 32. Further, molten polymer 96 flows so as to fill in thespace of cavity 93. Moreover, a part of the adhesive which composesfirst bonding layers 12 a, 12 b melts by the temperature at theinjection molding processing because melting point T3 is in the relationof T3<T1, and flows along with molten polymer 96.

Molded product 30 (refer to FIG. 3) in which surroundings of metalplates 31, 32 and first sheet material 11 are covered with molded part33 is obtained by molten polymer 96 spread in cavity 93 being cooled,and being solidified. First sheet material 11 and metal plates 31, 32are bonded through remaining first bonding layers 12 a, 12 b.

Because in the manufacturing method of a molded product according tothis embodiment, the molded part is formed by an injection moldingprocess, an expensive injection molding dies is needed, differing fromthe manufacturing method of a molded product according to theabove-mentioned embodiment. However, because in the manufacturing methodof a molded product according to this embodiment, the mold coating isperformed to laminate 90 of at least three-layer structure, mold polymersheet 20 shown in FIG. 2 is not needed. Therefore, the formation processof the laminate can be simplified compared with the manufacturing methodof a molded product according to the previous embodiment in whichlaminate 40 of at least five layer-structure is coated with moldingmaterial.

[Embodiment]

Two sheet of coppers (200 mm×280 mm and thickness t is 1 mm) wereprepared as a metal plate. Lap width L was 210 mm and the clearancebetween sheet coppers was 0.4 mm as shown in FIG. 3B, and the moldingarea (240 mm×250 mm) which includes the lap area was coated withmolding.

(Embodiment 1)

PPE sheet (Asahi Kasei Corporation, Zairon 540Z, and thickness t is 0.4mm) where the heat-hardening bonding layer had been spread on both sidesas shown in FIG. 1 was prepared. The sheet was cut into the size (220mm×230 mm) whose length and breadth is 10 mm larger than the lap area oftwo sheet coppers. Moreover, flame-resistant PE resin sheet (UBEINDUSTRIES, LTD. Z555, and thickness t is 2.5 mm) which the hot meltadhesive layer was spread on one side as shown in FIG. 2 was prepared.The flame-resistant PE resin sheet was cut (220 mm×230 mm×2.5 mm) sothat the volume of two flame -resistant PE resin sheet may become morethan the value obtained by subtracting the volume of the sheet copperand the PPE sheet from the volume of the molded product of 240 mm×250mm×5 km. Further, a frame body composed of lower metal frame 81 shown inFIG. 8 and an upper metal frame which makes couple with lower metalframe 81 was prepared.

The laminate piled up in order of a flame-resistant PE resin sheet, aresin sheet, a PPE sheet, a sheet copper, and a flame-resistant PE resinsheet was arranged in this frame body. This laminate was placed betweenhot pressing plates together with the frame body, and it was set in hotpressing molding machine heated to 130° C. The pressure of 0.5 MPa wasapplied after preheating enough, and the hot pressing processing wascarried out. As a result, the molded product (sample 1) which has thestructure shown in FIG. 7 was obtained.

As a result, in sample 1, a very thin and uniform insulating layer(spacer polymer) was formed between sheet coppers of 0.4 mm in theclearance and 200 mm in one side. Partial discharge generationdisappearance (10 pC) voltage in sample 1 was measured, and the value of8 kV or more was obtained. Moreover, the void which affects negativelyon electrical insulation did not generate between sheet coppers of thismolded product and around the sheet copper.

Moreover, the partial discharge generation disappearance voltage wasmeasured again after heat cycle of −25° C. to 105° C. was repeated 100times to this sample 1, and the same value of 8 kV or more as one beforeproviding the heat cycle were obtained. In a word, it was confirmed thateven if the heat cycle is added, the void and flaking off are notoccurred on the interface of the sheet copper and the PPE sheet, and thesheet copper and the PPE sheet are strongly bonded.

(Embodiment 2)

The same PPE sheet as embodiment 1 was made. Moreover, injection moldingdies 90 shown in FIG. 9 as a frame body was prepared.

The laminate piled up in order of a sheet copper, a PPE sheet and asheet copper was placed between hot pressing plates of a hot pressingmolding machine, and heated to 130° C. The bonding layer in the PPEsheet melted by this heating processing, and the sheet copper and thePPE sheet were bonded through the bonding layer. The injection moldingprocessing was carried out by injecting the flame-resistant PE resinmelted after having arranged this laminate in cavity 93 of injectionmolding dies 90. Thereby, the molded product (sample 2) which has thestructure shown in the FIG. 7 was produced.

As a result, in sample 2, a very thin and uniform insulating layer(spacer polymer) was formed between sheet coppers of 0.4 mm in theclearance and 200 mm in one side. Partial discharge generationdisappearance (10 pC) voltage in sample 2 was measured, and the value of8 kV or more was obtained. Moreover, the void which affects negativelyon electrical insulation did not generate between sheet coppers of thismolded product and around the sheet copper.

Moreover, the partial discharge generation disappearance voltage wasmeasured again after heat cycle of −25° C. to 105° C. was repeated 100times to this sample 2, and the same value of 8 kV or more as one beforeproviding the heat cycle were obtained. In a word, it was confirmed thateven if the heat cycle is added, the void and flaking off are notoccurred on the interface of the sheet copper and the PPE sheet, and thesheet copper and the PPE sheet are strongly bonded.

COMPARISON EXAMPLE 1

injection molding dies 110 shown in FIG. 11 as a frame body wasprepared.

The injection molding processing was carried out by injecting polyphenylether (PPE, Asahi Kasei Corporation, Zairon 540Z) melted after arrangingthe sheet copper in cavity 113 of injection mold 110 in cavity 113, andthe molded product (sample 3) was made.

Partial discharge generation disappearance (10 pC) voltage in sample 3was measured, and the very low value less than 1 kV or more wasobtained. This molded product was cut, and the section was observed. Asa result, it was confirmed that the void which affects negatively onelectrical insulation had generated between sheet coppers.

Although the present invention has been illustrated and described withrespect to exemplary embodiment thereof, it should be understood bythose skilled in the art that the foregoing and various other changes,omission and additions may be made therein and thereto, withoutdeparting from the spirit and scope of the present invention. Therefore,the present invention should not be understood as limited to thespecific embodiment set out above but to include all possibleembodiments which can be embodied within a scope encompassed andequivalent thereof with respect to the feature set out in the appendedclaims.

1. A molded product, in which surroundings of metal plates spaced atspecified intervals are covered with insulating polymer to insulate themelectrically, comprising: a spacer polymer arranged between said metalplates, which consists of insulating polymer whose melting point is T1,and a molded part, which covers surroundings of said metal plates andsaid spacer polymer, and consists of insulating polymer whose meltingpoint is T2(<T1).
 2. The molded product according to claim 1, whereinthe principal ingredient of said insulating polymer of melting point T1is aromatic polymer, and the principal ingredient of said insulatingpolymer of melting point T2 is polyolefine.
 3. The molded productaccording to claim 1, wherein the bonding layer composed of the adhesivemelting point T3 is in the relation of T3<T1 is provided between saidmetal plates and said spacer polymer, and between said metal plates andsaid molded part.
 4. The molded product according to claim 3, whereinthe first and second bonding layers composed of the adhesive thatmelting point T3 is in the relation of T3<T1 are provided between saidmetal plates and said spacer polymer, and between said metal plates andsaid molded part, respectively, and wherein each adhesive which composessaid first and second bonding layers has high compatibility.
 5. A methodof manufacturing a molded product, in which surroundings of metal platesspaced at specified intervals are covered with insulating polymer toinsulate them electrically, comprising the steps of: arranging a firstsheet material composed of insulating polymer whose melting point is T1between said metal plates spaced at specified intervals, arranging afirst sheet material composed of insulating polymer whose melting pointis T2(<T1) outside of the outermost metal plates, hot-pressing molding alaminate of the metal plates, the first sheet material, and the secondsheet material at a temperature higher than T2 but lower than T1,melting the second sheet material while securing the interval betweenthe metal plates by the first sheet material, and covering thesurroundings of the metal plates and the first sheet material with themolded part composed of insulating polymer whose melting point is T2. 6.A method of manufacturing a molded product, in which surroundings ofmetal plates spaced at specified intervals are covered with insulatingpolymer to insulate them electrically, comprising the steps of:arranging a first sheet material composed of insulating polymer whosemelting point is T1 between said metal plates spaced at specifiedintervals, arranging a laminate of the metal plates and the first sheetmaterial in the cavity of the injection mold, injecting insulatingpolymer whose melting point is T2 (<T1) heated and melted at atemperature higher than T2 but lower than T1 into the cavity, andcovering the surroundings of the metal plates and the first sheetmaterial with the molded part composed of insulating polymer whosemelting point is T2 while securing the interval between the metal platesby the first sheet material.
 7. The method of manufacturing a moldedproduct according to claim 5, wherein a plurality of said first sheetmaterials are arranged between the metal plates.
 8. The method ofmanufacturing a molded product according to claim 5, further comprisingthe steps of: providing as one first bonding layers and second layerswhich consist of adhesive whose melting point T3 is in the relationT3<T1 on surfaces of the first sheet material and surfaces of the metalbody sides of the second sheet materials, respectively, and afterhot-pressing molding, bonding the first sheet material to said metalplates by the first bonding layers, and said molded part to said metalplates by the second bonding layers.
 9. The method of manufacturing amolded product according to claim 8, wherein each adhesive whichcomposes the first bonding layer and the second bonding layer hascompatibility, and the first bonding layer are bonded to the secondbonding layer.
 10. The method of manufacturing a molded productaccording to claim 6, further comprising the steps of: providing as onefirst bonding layers which consist of adhesives whose melting point T3is in the relation of T3−T1 on surfaces of the first sheet material, andafter hot-pressing molding, bonding the first sheet material to saidmetal plates by the first bonding layers.